1. Field of the Invention
This invention relates to a shipping rack convertible to a first rack length for loading onto a semi-trailer and convertible to a second length for loading onto a railroad boxcar.
2. Prior Art
Racks of the type to which the present invention relates are commonly used for shipping industrial parts. The parts are normally elongated members which do not readily fit into box-like containers. For example, automobile bumpers are elongated and have a curved configuration which does not readily adapt to shipment in box-like containers. The racks used for this purpose normally have a bottom wall and upstanding end walls but no sidewalls. The elements to be shipped can be easily loaded onto the racks with the racks giving vertical and endwise support.
Loaded racks are normally shipped in conventional semi-trailers and railroad boxcars. The semi-trailers referred to are of the type normally pulled by a tractor on highways or, in some cases, shipped for long distances on railroad flat cars.
Both semi-trailers and railroad boxcars have assumed a relatively conventional width. For example, standard railroad boxcars have an interior width of about one hundred ten inches while many semi-trailers have an interior width of about ninety-eight inches. Racks are normally stowed in either railroad boxcars or semi-trailers lengthwise across the width of the railroad boxcar or semi-trailer. There must be a relatively snug fit of the racks across the width of these units so that the racks will not shift within the transporting unit for any appreciable distance while the unit is moving. Such shifting, if it gained momentum by traveling a foot or so within the transporting unit could cause severe damage to the unit possibly rupturing the sidewalls. It is, however, desired to have a small clearance between the ends of the racks and the sidewalls of the transporting unit, to facilitate loading and unloading and also to accommodate the small discrepancies in standard width which are encountered in practice. Two inches is normally considered adequate clearance.
In the past, two different sets of racks have had to be used to transport industrial parts in semi-trailers and railroad boxcars. The racks for semi-trailers have been about ninety-six inches in length while the racks for railroad boxcars have been about one hundred eight inches in length. This obviously requires industrial and shipping concerns to stock different size racks and, in addition to the cost of such racks, inhibits flexibility in loading and shipping materials. Thus, racks of railroad boxcar size might be available when it is desired to ship on semi-trailers or vice-a-versa.
In accordance with the present invention, a shipping rack is provided which may be used for loading either semi-trailers or railroad boxcars. The basic rack length is fashioned to be of a size desirable for semi-trailers in view of the fact that such trailers are narrower than railroad boxcars. However, extensions which are pivotable out of one of the end walls of the racks are provided to effectively increase the length of the rack so that it may be utilized for shipment via railroad boxcars. There is, of course, a certain amount of unused space in the boxcar when such extensions are used. However, the overall benefits derived from the lack of need for stocking two sizes of racks and the flexibility in use of the racks override this factor.